package org.jeecg.activiti.ActivitClass;

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.annotation.Configuration;

    /**
     * 上下文管理
     *
     * @author: Ace Lee
     * @create: 2019-04-22 15:24
     */
    @Slf4j
    @Configuration
    public class SpringContextHolder implements ApplicationContextAware, DisposableBean {

        private static ApplicationContext applicationContext = null;

        /**
         * 取得存储在静态变量中的ApplicationContext.
         */
        public static ApplicationContext getApplicationContext() {
            assertContextInjected();
            return applicationContext;
        }

        /**
         * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
         */
        @SuppressWarnings("unchecked")
        public static <T> T getBean(String name) {
            log.debug("从SpringContextHolder中取出Bean:" + name);
            assertContextInjected();
            return (T) applicationContext.getBean(name);
        }

        /**
         * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
         */
        public static <T> T getBean(Class<T> requiredType) {
            assertContextInjected();
            return applicationContext.getBean(requiredType);
        }

        /**
         * 清除SpringContextHolder中的ApplicationContext为Null.
         */
        public static void clearHolder() {
            log.info("清除SpringContextHolder中的ApplicationContext:"
                    + applicationContext);
            applicationContext = null;
        }

        /**
         * 实现ApplicationContextAware接口, 注入Context到静态变量中.
         */
        @Override
        public void setApplicationContext(ApplicationContext applicationContext) {
//		logger.debug("注入ApplicationContext到SpringContextHolder:{}", applicationContext);

            if (SpringContextHolder.applicationContext != null) {
                log.warn("SpringContextHolder中的ApplicationContext被覆盖, 原有ApplicationContext为:" + SpringContextHolder.applicationContext);
            }

            SpringContextHolder.applicationContext = applicationContext; // NOSONAR
        }

        /**
         * 实现DisposableBean接口, 在Context关闭时清理静态变量.
         */
        @Override
        public void destroy() throws Exception {
            SpringContextHolder.clearHolder();
        }

        /**
         * 检查ApplicationContext不为空.
         */
        private static void assertContextInjected() {
            if(applicationContext == null) {
                throw new IllegalStateException("applicaitonContext属性未注入, 请在applicationContext.xml中定义SpringContextHolder或在SpringBoot启动类中注册SpringContextHolder.");
            }
        }
    }


